Paper is the term generally used to describe sheet materials made up of many small discrete fibers, most typically cellulosic fibers, bonded together. The source of the raw material used in the manufacture of paper is many and varied, but the dominant source is cellulosic fiber in the form of wood pulp.
In the typical papermaking process, pulp is generally beaten and refined as an aqueous slurry. Various mineral pigments may be added in a filling and loading step. The paper also may undergo a sizing treatment, which may involve adding materials to the paper in order to render the sheet more resistant to penetration by liquids, particularly water. Rosin, hydrocarbon and natural waxes, starches, glues, casein, asphalt emulsions, synthetic resins, and cellulose derivatives are among the materials used as sizing agents in the prior art. The agents may be added directly to the stock as “beater additives”. In the alternative, a dry formed sheet may be passed through a size solution or over a roll wetted with a size solution. Sheet forming occurs, typically using a Fourdrinier paper machine, whereby the pulp slurry is poured onto wires, pressed and dried. Optionally, paper may be finally “converted” by undergoing some further treatment after manufacture. Among the many converting operations are embossing, impregnating, saturating, laminating, coating and sheeting. The above steps and variations thereof are well-known; see Kirk-Othmer, Encyclopedia of Chemical Technology, Second Edition, Vol. 14, pp. 494 et. seq. Varieties of cellulosic fiber and/or pulp sources, fillers, sizing agents, converting operations, and the like are also described in G. A. Smook, Handbook for Pulp & Paper Technologists, Second Edition.
The performance variables of paper sheets vary greatly depending upon the vast array of end-uses for such sheets. For laser printing, in particular, it is desirable to achieve paper sheets that minimize jamming, curls, wavy at the edges, and asymmetric shrinkage of a sheet when it is being fused. These needs are satisfied, the limitations of the prior art overcome, and other benefits realized in accordance with the principles of the present invention by providing the paper sheet as described herein.